1. Field of the Invention
This invention relates to packaging substrates and methods of fabricating the same, and, more particularly, to a packaging substrate having a passive element and a method of fabricating the same.
2. Description of Related Art
With the rapid development of semiconductor package technology, passive elements are in increasing demands. Passive elements do not affect the basic characteristics of signal, but only allow the signals to pass therethrough. Passive elements include capacitors, resistors and inductors. Compared to active elements, the passive elements have their resistances unchanged even when voltages or currents change, because the passive elements do not participate in electron exercises.
Any product that is driven by electricity needs passive elements that provide electrical loop controlling functions. Such applications include 3C and other industrial fields. Please refer to FIG. 1, which is a cross-sectional diagram of a packaging substrate having a passive element according to the prior art. A passive element 12 is disposed on conductive pads 11 on a substrate 10 by means of solder bumps 13.
With the development of technology, electronic devices are designed to meet the low-profile and compact-size requirements. However, a package structure of the prior art, in which the passive element 12 is disposed on the substrate 10, has an increased height, and is adverse in the thinning design for the electronic devices. Since the passive element 12 is disposed on an external surface of the substrate 10, a signal transmission route between an interlayer circuit and a passive element of the substrate 10 is very long, which results in the loss of electricity and electrical functionality. Also, the surface of the substrate 10 is occupied by a circuit layout, so an area within which passive elements may be disposed is very limited. Therefore, only a small number of passive elements may be disposed on the substrate 10. As the number of passive elements increases, the area reduction of the circuit layout is inevitable.
Therefore, how to avoid the drawbacks of the packaging substrate having a passive element of the prior art is becoming one of the popular issues in the art.